Line choke coil



y 19-50 M. .1. BROWN 2,515,983

LINE CHOKE con.

Filed June 2, 1947 2 Sheets-Sheet 1 Fig].

INVENTOR flyron JBrowzz.

ATTOR EY M. J. BROWN LINE CHOKE COIL July 18, 1950 2 Sheets-Sheet 2 Filed June 2, 1947 INVENTOR Myron Jfiro H72.

BY I? ATTOR EY WITNESSES:

Patented July 18, 1950 westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application 'Ju'ne 2, 1947, Serial No. 751,776

3 Claims. 1

The present invention relates to line choke coils, which are intended to be connected inserice in a transmission or distribution line to carry the normal, relatively low-frequency power current, and to interpose a high impedance to highfrequency carrier currents, which may be superimposed on the power current for communication or other purposes. The choke coil of the present invention is particularly adapted for use in connection with carrier current telephone systems on rural lines, although its usefulness is not necessarily restricted to this particular application.

The principal object of the present invention is to provide a line choke coil of rugged, weatherdirectly on the coil support itself, resulting in a" simple and low-cost construction.

Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment, taken in connection with the accompanying drawings, in

which:

Figure 1 is a view in elevation of a choke coil embodying the invention connected in a. line;

Fig. 2 is an end view of one end of the choke coil;

Fig. 3 is a longitudinal section view, approximately on the line III--III of Fig. 2;

Fig. 4 is an end view of the other end of the choke coil; and

Fig. 5 is a top plan view of the coil support,

- with the coil broken away.

. The choke coil of the present invention is intended to be connected in series in a transmission .or distribution line, as shown in Fig. 1, where the coil l is shown connected in series between line conductors 2 and 3. The coil is designed to have low,or substantially negligible, impedance at the frequency of the power current, which is usually sixty cycles per second, and to have very high impedance at the frequency of the carrier currents which may be superimposed on the power current, which may be of the order of 100 or 150 kilocycles per second, for example.

The construction of the new choke coil is shown in detail in Figs. 2 through 5. The choke coil I is supported on a tubular coil support 4, which may be made of porcelain or other suitable insulating material. The coil support 4 preferably has a plurality of circumferential ribs or projections 5 on its outer surface, each of which is interrupted at two circumferentially spaced points to form, in effect, longitudinal grooves 8 extending through the ribs 5. A strain member 1 is secured within the tubular coil support 4. The strain member 1 may also be made of porcelain, or other suitable insulating material which has sufiicient mechanical strength. As shown in the drawings, the strain member 1 is generally cylindrical and has two slots 8 and 9 formed in it in mutually perpendicular planes, one slot extending to one end of the strain member, and the other slot extending to the other end, for reception of the line conductors 2 and 3. The strain member "I may be secured in the tubular coil support 4 in any suitable manner, as by glazing it in place if both members are made of porcelain. Terminals l0 and H of any suitable type are mounted on opposite ends of the tubular coil support 4 by threading them into internally threaded holes in the ends of the coil support.

The coil l is supported on the outside of the tubularcoil support 4. The coil l preferably consists of a plurality of sections l2, which may be spaced apart in order to control the distributed capacitance so as to obtain the desired impedance at the carrier frequency, and which are connected together in series, as indicated at 13. The coil sections l2 do not rest directly on the coil support 4, but are supported and held in place by a mass of rigid insulating material M, which is molded around the coil sections and which engages the ribs 5 on the coil support to hold the coil v proof. and moisture-resistant.

Since the coil 1 is to be connected in seriesin f a line, it might be damaged by voltage surges on the line resulting from lightning strokes, switch- ,ingoperations, or other causes, and the coil is protected against such damage by means of a spark-gap device, which is mounted directly on the coil support 4. One end of the coil support 4 has a recess l5 formed in it, as clearly shown in Fig. 5, and the spark-gap device consists of two electrodes l6 and I! mounted on the end of the coil support 4 and positioned to form a spark gap between them over the recess l 5.

The electrodes [6 and I! may be arcuate members of brass, or other suitable metal, and they I claim as my invention: are connected across the coil I. The electrode l B 1. A choke coil comprising a tubular member of is secured in place by means of a screw l8 insulating material, a slotted, insulating strain threaded into an internally threaded hole in the member secured within the tubular member, a end of the porcelain tube 4, and a copper strap 5 rigid mass of insulating material supported on conductor I9 is also clamped under the screw the tubular member, a coil comprising a plurality 18 in contact with the electrode 16. The conof series-connected multi-turn sections, said coil ductor l9 extends longitudinally through one -.of sections being embedded in saidmass of insulatthe groovesB on the surface of the coilsupport 4 .ingimateriatian'd spacedxapart axially ofthe tubuto the opposite end, and is clamped under the 10 lar member, and terminal means for the coil on terminal III at that end in electrical contact with .ithe tubular member.

the terminal. One terminal lead 20 of the coil 2. A choke coil comprising a tubular member I extends through the insulating material "I 4 and i of insulating material, a slotted, insulating strain is soldered to the conductor 19. 'Thus, the termie membersecured-within the tubular member, said nal I0 is electrically connected to oneendof; the tnbulari'memberfhaving circumferential ribs on coil l and to one electrode I6 ofthe protective gap. 1-. its-souterrsiirfac and having a recess in one end The other electrode ll of the. gapis clamped in .thereof, a rigid mass of insulating material supposition on the end of the coil support E'by'the portedon'thetubular member and engaging said terminal H, and a copper strap conductorz fl' is ribs, -.-:a: coil comprising a plurality of series-conalso clamped under the terminal ll, so as to be nected multi-turn sections, said coil sections being in-contact with both the terminal and the. elec- \.embedded in said nass ofiinsulatingmaterialand .trode' H. The conductorll extends for ashort .spa'ced ;apart.iaxiallyaof .the tubular-member,

distance longitudinally of the coil support in the ...'terminal.me ans.forthecoil on the tubular-memother groove 6,;and the other terminallead 22 of f.ber,.and.two,'electrodemembers mountedon said the-coilis soldered to the conductor -'2l,,so. that oneendoflthe tubular member and-disposedto this end. of. the coil is electrically 'connectedto .form a, gap between them over said recess inthe thefterminal II- and to'the electrode 11. .,.tubular..member, .saidelectrode .members being Inuse, the choke coil I is interposed directly ilelectricall connected to said terminal means .so me; transmission or distribution line as shown in 'lthatIthe gap-is across. the coil.

Fig.1. The line. conductors 2- and 3 are looped .3 ...A.choke.coilcomprising.a..tiibular.memberof through the respective slots 8 and 9 of'the. strain ,ins'ulating'material, .a slotted, insulating strain [member 1, and the. ends of the conductors are member 'secured -withinthe.tubularimember said carried to the terminals l0 and II, respectively, .-.tubular member.havingcircumferentialribson its softhatthercoil is connected/in series in" the .outer. surface and having .a recess in. one end "line; The strain member? takes the stresses 1111135 thereof, a 'rigid-..mas's..of insulating materialsupposed by the line conductors; and no stressisim- .,ponted..on theltubulanrnember and engaging said 'jpose'd on the coil support 4 or on the terminals. iiibs,v.a}coil.comprising aplurality. of.series-con- Th l l ispretected f m d ma eidu to surg .necte dmulti-turn sections, said coil .sections voltae s t line y t c n t e. 1 b einglembedded' .in. said mass of insulating .ma-

Qtrod and Which bTeakS'dOWn y simg.terial..and spaced v.apart axially of the tubular lthe'coil upon t Oc re ce of .9 dangerous Surge member, terminalmeans for the coilon opposite Vo t S ce the arc between the' electrodes ,endsof. the tubu1ar.membe r,'two felectrode memj occurs'opp t the recesslt; t. is spaced way rbersimounte'don said. one .end of trieztubuiar 'from the porcelain tube 4,. and thus'there visf'no meiriheranddisposed to form a, gap between them "Hanger of cracking Otherwise a in he;3 .l over. said recessjiriithe tubular member means porcelain, v ush the l ere y "for electrically.connecting one or said electrode upported on the end of the tube. .members to. thetcrminal means at one end of the 'It'should ow be pp t that a line'choke .tiibiilar member,andmeans for "electric'allycon- .coil' has been provided. which is of inexpensive nejtingthe otheiifdf the fleet-m d membersto co s u t o and which is rug ed and weathernthe terminalrneansa't the other end of the tubular proof. The new "choke coilcan be'jmounte'dp'dimb r; vjrectly' in the line itself, thus avoiding'the' dis- I VMYRON JHBR'OWN. advantages of separate mounting and resulting" in 'a'simble, low-"cost"installation. The'n'ewbhoke 'ItEFERENCES CITED icofl' is particularly suitable for use I 9 The following references are of record inwth "current telephone. systems onrural' distr bution file ofqthjsDpatent: lines, where low cost is an important considera- "'tion; but it will be apparent that it may alsobe I v 'ST PATENTS used in other types of carriercurrent systems. Number Name Date A' pr eferred embodiment of the'invention'has no 524,850 Hammond Aug. 21,1894 "been'shown'and described for the purpose ofillus- 625,632 Adams jet al. -L May. 23,. 1899 "-tration, but it" is to be understood that various 1,211,822 Chernyshoff 'Jan.'9, 1917 other embodiments are possible within thescope 1211453 Jackson Feb. 27, 1917 '"of the invention. The inventionisnot limited, f:"1-",5 1'7,'770f Ziegler Dec. 2, 1924 therefore, to'the particular details of -'con'struc- 1,745,812 Ready "Feb:14, 1-930 'ition shown, but in its broadest aspects, it-includes I',920',162 Amyiet al; "July25, 1933 '7 claims. 

